In species where cells are not all in contact with the external environment, a circulatory system delivers oxygen, hormones, and nutrients and removes waste products. Open systems allow the circulatory fluid (hemolymph) to spill out into a cavity to exchange substances. Closed systems contain the blood at all times, while interstitial fluid surrounds tissues and organs. Blood vessels include arteries, veins, and capillaries which carry blood to and from the heart and can constrict or expand (vasoconstriction and vasodilation) to change blood pressure and assist in thermoregulation. Blood contains plasma, red blood cells, white blood cells, and platelets, and the heart pumps blood around the system according to the cardiac cycle. This lecture also covers oxygen and CO2 transport via hemoglobin in red blood cells.
Arteries have thick walls and
carry blood away from the heart. Veins carry blood towards the
heart, have thinner walls and have valves to prevent backflow.
Capillaries are small vessels
with very thin walls across which nutrients, hormones, gases and
waste products can diffuse.
Blood contains fluid called
plasma, as well as red blood cells and white blood cells. Red blood
cells (erythrocytes) contain hemoglobin and transport oxygen. White
blood cells (leukocytes) function in immunity. Platelets are cell
fragments that play a role in clotting.
Red blood cells contain
hemoglobin, a four subunit protein that binds cooperatively to
The mammalian heart has four
chambers. The right atrium and ventricle pump blood through the
pulmonary circuit and the left atrium and ventricle pump blood
through the systemic circuit.
The sinoatrial node (SA) node
is the pacemaker for the heart.
Deoxygenated blood leaves
organs and returns to the heart via the superior vena cava and the
inferior vena cava. Blood drains into the right atrium and then
enters the right the right ventricle. Blood is pumped through the
pulmonary arteries into the lungs and the newly oxygenated blood
returns to the heart via the pulmonary veins, draining into the left
atrium and then the left ventricle. The left ventricle pumps blood
through the aorta to tissues and organs.
The Circulatory System
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
The book and CD package include two full length practice exams that are presented with all questions answered and explained. The author also presents detailed reviews of all test topics and includes multiple-choice and free-response questions with answers at the end of each topic's chapter.
This book includes a review of the AP Biology exam format and scoring, proven strategies for answering multiple-choice questions, and hints for tackling the essay questions. The practice tests include answers and explanations and there is also proven test-taking strategies for both the multiple choice and essay parts.